Development and Application of Cleaning Grading Method for Pipes in Water Distribution Networks

To ensure a stable supply of potable drinking water, effective management of the distribution system, starting from the reservoir to the consumer water-supply facility, is essential. Following the 2019 flood in Incheon Metropolitan City, Korea has mandated that transmission and distribution pipelines be cleaned at least once every 10 years. However, budgetary and management constraints make it difficult to clean all pipelines, especially in complex underground water supply systems spanning vast areas. This study evaluated seven cleaning-grade criteria proposed in previous studies for a medium-sized block in one region of Korea, and compared the rating results based on different combinations of these criteria. Additionally, a grouping-based assessment based on flow direction was performed to propose a feasible rating method. The findings revealed that methodologies from previous studies tended to apply overly strict criteria for cleaning grades, overlooking potentially hazardous pipelines that could lead to water quality accidents. Furthermore, using a cross-sectional evaluation criterion, without clearly established weights for each of the seven application criteria, is limited as it fails to consider potential risks. Therefore, prioritizing the weighting of individual criteria and conducting a group-based evaluation that facilitates practical judgment can support the development of a mid- to long-term pipeline maintenance plan.